Dmitry Medvedev has been caught making some unusual comments off-air after failing to realise television cameras were still rolling.

The Russian prime minister let his guard down after an interview with five Russian television stations - offering his strange views on Father Christmas and aliens as well as taking a pot shot at President Vladimir Putin and the federal police.

"I believe in Father Frost. But not too deeply. But anyway, you know, I'm not one of those people who are able to tell the kids that Father Frost does not exist," he said in a jovial reply to a question about Russia's equivalent of Santa Claus.

He went on to take a jab at Mr Putin for his frequent lateness for meetings after he was more than hour late for an event in southern Russia.

"Colleagues, somebody should be extremely punctual, while somebody else is exhausting all the limits for being late," he said.

The comments invited a satirical reaction on the Internet which is unlikely to help Mr Medvedev, whose power has been ebbing since Mr Putin took over as president.

The prime minister speaking to the TV stations that caught him off-air

In the interview itself, Mr Medvedev underlined his allegiance to the president in a likely bid to dismiss rumours he is about to be fired.

In an unexpected move, the liberal-leaning prime minister defended Kremlin-backed laws which critics say will be used to stifle dissent.

But in the off-air comments, he was more frank.

When a journalist complained about federal investigators arriving to search the home of a witness in an inquiry early in the morning, Mr Medvedev said: "They are just jerks, so they come at eight in the morning.

"It's just their set of habits. I know many people who work in the police. They think if they come at seven in the morning they will get everything in the world."

Another of the journalists asked whether the president is handed secret files on aliens when he receives the briefcase needed to activate Russia's nuclear arsenal.

"Along with the briefcase with nuclear codes, the president of the country is given a special 'top secret' folder. This folder in its entirety contains information about aliens who visited our planet," Mr Medvedev answered playfully.

"Along with this, you are given a report of the absolutely secret special service that exercises control over aliens on the territory of our country...

"More detailed information on this topic you can get from a well-known movie called Men In Black... I will not tell you how many of them are among us because it may cause panic," he said.

None of the television stations that interviewed Medvedev broadcast the off-air comments.

Russians mocked the prime minister on the internet.

"It's sad when the former president and current prime minister of your country is simply a pathetic person," Yekaterina Kudinova wrote on Twitter.